Development of theoretical models for dimensions of single-layer multi-track and multi-layer multi-track depositions by μ-PTA additive manufacturing process

Abstract

This paper presents development and experimental validation of theoretical models to evaluate layer thickness of single-layer multi-track deposition, total height and total width of multi-layer multi-track depositions by micro-plasma transferred arc additive manufacturing (μ-PTAAM) process. The models have been developed as function of μ-PTAAM process parameters and thermal properties of deposition and substrate materials and considering formation of circular concave fillet between two adjacent deposition tracks. These features have made them generic models which can be used for any combination of deposition and substrate materials and for any form of deposition material i.e. wire, powder, particulate or their combination. Models of multi-layer multi-track deposion can alternatively used to compute number of deposition layers required to achieve given deposition height and number of deposition tracks required to achieve given deposition width. Experimental validation found prediction errors in a range from −9.7 to 9.2% for layer thickness of single-layer multi-track deposition; −5.3 to 11.1% for total height and −4.8 to 7.8% for total width of multi-layer multi-track deposition. Considerable narrow ranges of prediction errors validate the developed models and also imply that the developed model slightly under-predicts or over-predicts deposition layer thickness. It was found that deposition layer thickness increase with increase micro-plasma input power and volumetric material deposition rate, and decreases with increase in micro-plasma torch travel speed. The developed models will be useful for different coating, cladding, and surface texturing applications, freeform manufacturing of different products, minimizing post-processing requirements, and deposition material wastage thus improving techno-economic aspects of μ-PTAAM process.